10. Stages of DevelopmentStages of Development
of the kidney:of the kidney:
• Human kidney is developed fromHuman kidney is developed from
intermediate mesoderm and passesintermediate mesoderm and passes
through 3 stages :through 3 stages :
1-1- PronephrosPronephros
2-2- MesonephrosMesonephros
3-3- MetanephrosMetanephros
Dr. Sherif Fahmy
14. PRONEPHROSPRONEPHROS
• Appears at 4Appears at 4thth
week. Inweek. In cervicalcervical region, cranialregion, cranial
part of intermediate mesoderm is segmentedpart of intermediate mesoderm is segmented
into 7 nephrotomes which become cavitated tointo 7 nephrotomes which become cavitated to
form 7form 7 pronephric tubulespronephric tubules..
• Each tubule has 2 ends:Each tubule has 2 ends: 1-1- lateral ends:lateral ends: join tojoin to
form pronephric duct.form pronephric duct. 2-2- medial ends:medial ends: join thejoin the
coelomic cavity.coelomic cavity.
• Lower end of pronephricLower end of pronephric ducts join the cloacaducts join the cloaca..
• Pronephric tubules and proximal part of its ductPronephric tubules and proximal part of its duct
degenerate Leavingdegenerate Leaving caudal part of the duct ascaudal part of the duct as
mesonephric duct.mesonephric duct. Dr. Sherif Fahmy
17. MESONEPHROSMESONEPHROS
• It appears at theIt appears at the 66thth
weekweek as 2 bulges onas 2 bulges on
posterior abdominal wall forming ovoidposterior abdominal wall forming ovoid
mesonephric ridges.mesonephric ridges.
• It is middle part of the intermediate mesodermIt is middle part of the intermediate mesoderm
that liesthat lies in thoracicin thoracic andand upper lumbarupper lumbar region.region.
• It is divided into segments which becomeIt is divided into segments which become
canalised to form S-shapedcanalised to form S-shaped mesonephricmesonephric
tubulestubules..
• Medial ends formMedial ends form internal glomeruliinternal glomeruli while lateralwhile lateral
ends joinends join mesonephric ductmesonephric duct which open inwhich open in
primitive urogenital sinus.primitive urogenital sinus. Dr. Sherif Fahmy
21. Fate of MesonephrosFate of Mesonephros
• 1-1- Tubules:Tubules:
– Males:Males: form vasa efferentia, lobules of epididymisform vasa efferentia, lobules of epididymis
(head of epididymis) and paradidymis.(head of epididymis) and paradidymis.
– Females:Females: form epoophoron and paroophoron.form epoophoron and paroophoron.
2-2- Duct:Duct:
-- Males:Males: Appendix of epididymisAppendix of epididymis,, Epididymis, vasEpididymis, vas
deferens, seminal vesicle, ejaculatory duct, ureterdeferens, seminal vesicle, ejaculatory duct, ureter
and trigone of urinary.and trigone of urinary.
- Females:Females: Gartner duct, ureter and trigone ofGartner duct, ureter and trigone of
urinary bladder.urinary bladder.
At the 8At the 8thth
week most of mesonephric tubulesweek most of mesonephric tubules
degenerate.degenerate.
Dr. Sherif Fahmy
29. KIDNEY AND URETERKIDNEY AND URETER
1-1- Metanephros:Metanephros:
• It isIt is caudal part of intermediate mesodermcaudal part of intermediate mesoderm inin
the pelvic cavity. It formsthe pelvic cavity. It forms metanephric capmetanephric cap
(blastema) which divides into small masses(blastema) which divides into small masses
following divisions of the ureteric bud. Eachfollowing divisions of the ureteric bud. Each
mass is calledmass is called renal vesiclesrenal vesicles..
• EachEach vesiclevesicle will formwill form Bowman’s capsule,Bowman’s capsule,
proximal convoluted tubule, loop of Henel andproximal convoluted tubule, loop of Henel and
distal convoluted tubules.distal convoluted tubules.
Dr. Sherif Fahmy
34. 2-2- Ureter:Ureter:
• It arises fromIt arises from dorsum of mesonephric ductdorsum of mesonephric duct..
• ItIt elongates dorso-craniallyelongates dorso-cranially to be in contact withto be in contact with
metanephros which will form themetanephros which will form the metanephric capmetanephric cap..
• Upper end of the ureter divides to formUpper end of the ureter divides to form 2 – 3 major2 – 3 major
calycescalyces, which further divides into many, which further divides into many minor calycesminor calyces
which divide intowhich divide into collecting tubulescollecting tubules..
• Each collecting tubules will be covered with aEach collecting tubules will be covered with a piece ofpiece of
thethe metanephric capmetanephric cap which form renal vesicles whichwhich form renal vesicles which
forms rest of the nephron except the collecting tubulesforms rest of the nephron except the collecting tubules
which is developed from dividing ureteric bud.which is developed from dividing ureteric bud.
• Collecting tubulesCollecting tubules communicatecommunicate with the rest of thewith the rest of the
nephron.nephron. Dr. Sherif Fahmy
35. Changes of external features ofChanges of external features of
developing kidney:developing kidney:
• Ascend of the kidney:Ascend of the kidney: It ascends fromIt ascends from
pelvic cavity to its adult site in the lumbarpelvic cavity to its adult site in the lumbar
region on posterior abdominal wall. This isregion on posterior abdominal wall. This is
done by dorso-cranial elongation of thedone by dorso-cranial elongation of the
ureter pushing the kidney.ureter pushing the kidney.
• Change of blood supply:Change of blood supply: during ascend.during ascend.
• Loss of fetal lobulation:Loss of fetal lobulation: surface of thesurface of the
kidney becomes smooth.kidney becomes smooth.
• Change of direction of hilum:Change of direction of hilum: fromfrom
anterior to medial.anterior to medial. Dr. Sherif Fahmy
36. CONGENITAL ANOMALIESCONGENITAL ANOMALIES
A-A- KIDNEYKIDNEY
• Renal agenesis:Renal agenesis: Unilateral or bilateral.Unilateral or bilateral.
• Congenital polycystic kidney:Congenital polycystic kidney: due to failure ofdue to failure of
communication between collecting tubules and rest ofcommunication between collecting tubules and rest of
the nephron.the nephron.
• Horse shoe kidney:Horse shoe kidney: due to fusion between lowerdue to fusion between lower
ends of both kidneys. Ascent is arrested at level of L3ends of both kidneys. Ascent is arrested at level of L3
vertebra.vertebra.
• Pelvic kidney:Pelvic kidney: due to failure of ascend.due to failure of ascend.
• Ectopic kidney:Ectopic kidney: abnormal site of the kidney.abnormal site of the kidney.
• Aberrant renal artery:Aberrant renal artery: additional artery thatadditional artery that
supplying the kidney.supplying the kidney.
• Persistence of fetal lobulation:Persistence of fetal lobulation: surface of thesurface of the
kidney shows lobulations.kidney shows lobulations.
Dr. Sherif Fahmy
40. CONGENITAL ANOMALIESCONGENITAL ANOMALIES
B-B- UreterUreter
• Bifid ureter:Bifid ureter: Splitting of the upper part ofSplitting of the upper part of
the ureter.the ureter.
• Double ureter:Double ureter: Two separate uretersTwo separate ureters
due to formation of 2 ureteric buds.due to formation of 2 ureteric buds.
Dr. Sherif Fahmy
